An optical device including a mechanism for image projection and position detection is known. The optical device contains an image projecting mechanism and a mechanism to detect objects that exist on the projected image, and includes a technology that inputs data through a projected virtual input terminal.
However, with the conventional technology, the image projecting mechanism and the position detecting mechanism each use an independent optical mechanism, and due to size or geometric restrictions, miniaturization is difficult, and the position detection range is also geometrically restricted.